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ABSTRACT: Due to its superior power-to-weight ratio, a hydrostatic dynamometer is an ideal candidate for transient engine or powertrain testing. It can load or motor the engine to follow any desired speed and acceleration profiles for real-world applications. Given its high bandwidth, the hydrostatic dynamometer can be further used to emulate the dynamics of hybrid powertrains and, therefore, investigate the interactions between the engine and the hybrid power source in real time. This will greatly expedite the research of various hybrid powertrain architectures and control methodologies, without actually building the complete physical system. This paper presents the design, modeling, tracking control, and experimental investigation of a transient hydrostatic dynamometer. A ninth-order physics-based dynamic model for the dynamometer is formulated and then identified and validated with experimental data. To control the dynamometer to emulate the real-world engine speed/torque profiles, two different nonlinear control strategies are investigated and implemented. First, a nonlinear model-based inversion plus PID control is designed to achieve precise tracking. Then, a state feedback control via feedback linearization is designed and implemented. Experimental results demonstrate precise tracking performance with less than 5% tracking error for both transient and steady-state operations.
IEEE Transactions on Control Systems Technology 12/2011; · 1.77 Impact Factor
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ABSTRACT: As one of the most promising approaches for reducing automotive fuel consumption, hybrid powertrain has inspired extensive research efforts on system control and energy optimization. However, the time and cost of constructing or modifying a physical hybrid powertrain seriously affects the experimental investigation of the complicated system dynamics, so as to limit the development of the precise hybrid powertrain control and optimization. To provide an accurate and flexible hybrid powertrain emulation tool for developing the hybrid control methodologies, a rapid prototyping hybrid powertrain research platform, which employs a transient hydrostatic dynamometer to emulate the dynamics of various hybrid power sources and different hybrid architectures, is constructed. In this research platform, a three-level closed-loop control system is designed for realizing the hybrid powertrain emulation. With respect to the high/middle/low level systems, a suite of hybrid powertrain controllers including an adaptive driver model, an energy optimization strategy, a virtual hybrid torque controller and a dynamometer torque controller are designed and, further, their interactions are analyzed. Experimental results demonstrate that the proposed control system can achieve the precise emulation of the typical hybrid powertrain operation.
American Control Conference (ACC), 2011; 08/2011
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IEEE Trans. Contr. Sys. Techn. 01/2011; 19:1578-1586.
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ABSTRACT: Traditionally automotive powertrain research and development have been conducted with electromagnetic dynamometers. The ever increasing demand for reducing fuel consumption and emissions has driven the innovation of new technologies in engines, transmissions, and hybrid systems, which in turn requires significant flexibilities and transient capabilities of the dynamometer. Given its superior power density, hydrostatic dynamometer is an ideal candidate for the next generation transient dynamometers. This paper presents the design, modeling, and control of a hydrostatic dynamometer as a precise torque device that could control the amount of torque supplied in real-time under both steady state and transient operations. The mathematical models are constructed for the system. Based on the analysis and simulation of the dynamic model, the dynamometer is decoupled into two subsystems. For the power output control subsystem, a nonlinear tracking controller based on feedback linearization and internal model principle is designed; for the operating pressure control subsystem, a PID regulator is designed. Simulation results in AMESim environment demonstrate the fast dynamic response and precise tracking capability of the proposed control system.
American Control Conference, 2009. ACC '09.; 07/2009
